1. Field of the Invention
The present invention relates to a therapeutic device which performs vaporization, incision, resection, enucleation of a living tissue, such as the prostate, by means of electrical resection under observation by an endoscope, and to a resectoscope and a method of ablating a living body tissue.
2. Description of the Related Art
In general, a resectoscope is used for transurethral resection (TUR) and transcervical resection (TCR). This apparatus mainly includes an elongated hollow outer sheath, an optical scope (also referred to as “scope”) which is an endoscope for observation, and an electrode unit for resecting a living body tissue. The outer sheath is inserted in a body cavity. The optical scope and the electrode unit are inserted in the outer sheath.
Jpn. Pat. Appln. KOKAI Publication No. 5-220172 (Patent Document 1) shows an example of a resection electrode of a medical resectoscope for use in, e.g. excision of the prostate. In this apparatus, the resection electrode is projectably/retractably provided in a hollow shaft of the resectoscope. The resection electrode includes a pair of long rods, and a resection loop. The resection loop is bent in a semi-circular shape in the state in which the resection loop is bent at about 90° between the distal end portions of the paired rods. Further, a spacer is attached in front of the resection loop. The spacer restricts the depth of resection of the resection loop.
When the apparatus of Patent Document 1 is used, a high-frequency power is turned on. Then, the resection electrode is projected from the hollow shaft of the resectoscope. In this state, the resection electrode is moved back and forth, and thereby the prostate is resected. At this time, the resection electrode is pulled toward the near side. Thus, the prostate is resected by the resection loop.
At the time of the operation of resecting a piece of tissue by pulling the resection loop, the spacer is kept in contact with the surface of the tissue. As a result, the depth of resection of the resection loop is automatically restricted, and the resection loop is prevented from advancing to a depth that is greater than the depth restricted by the spacer.